1. Field of the Invention
The present invention relates to shift apparatuses, and particularly to workpiece shift apparatuses used for punch presses.
2. Related Art
Various electronic devices are ubiquitous in modern society. For example, computer servers and routers pervade the business world. Many such electronic devices generate a lot of heat during normal operation. This can deteriorate their operational stability and damage associated electronic devices. Thus a number of vents are defined in such electronic devices for facilitating heat dissipation.
Conventional means for machining vents in a workpiece comprise, for example, laser machining and different types of punch machining. However, laser machining is costly and is therefore not widely used. A first type of conventional punch machining requires manual manipulation to control movements of workpieces. This is slow and unsafe. Furthermore, the workpieces are liable to be imprecisely machined. In a second type of conventional punch machining, cams are used to control movements of workpieces. However, when adjacent vents are spaced far apart, large cams and correspondingly large piston cylinders having large diameters and long ranges of movement are needed. A large punch press is thus needed, which is unduly costly.
An improved workpiece shift apparatus for a punch press which overcomes the above-mentioned problems and shortcomings is desired.
Accordingly, an object of the present invention is to provide a workpiece shift-apparatus which can readily and precisely move workpieces on a punch press.
To achieve the above-mentioned object, a workpiece shift apparatus in accordance with the present invention comprises a die set, a bottom plate securely attached on the die set, a middle plate slidably attached on the bottom plate, and a top plate slidably attached on the middle plate. A vertical piston cylinder is located below the die set, and has a vertical piston rod extending through the die set. A vertical location pin extends from a free end of the vertical piston rod, and is vertically moveable with the vertical piston rod. A first horizontal piston cylinder is installed on the bottom plate. The first horizontal piston cylinder has a first horizontal piston rod extendable in a first direction. A first handspike extends away from and is moveable with the first horizontal piston rod. The first handspike is engaged with the middle plate. A second horizontal piston cylinder is installed on the middle plate. The second horizontal piston cylinder has a second horizontal piston rod extendable in a second direction which is perpendicular to the first direction. A third horizontal piston cylinder is installed on the middle plate. The third horizontal piston cylinder has a third horizontal piston rod extendable in the first direction. A second handspike extends directly from the third horizontal piston rod, and is moveable with the third horizontal piston rod in the first direction. The third cylinder and the second handspike are moveable with the second horizontal piston rod in the second direction. The top plate defines a plurality of location holes for respective insertion of the location pin. The middle plate and the top plate are moveable in the first direction by the first handspike pushing the middle plate. The second handspike is sequentially engaged in cutouts defined in the top plate. The top plate is moveable in the second direction by the second handspike pushing the top plate.